Abstract:

This experiment aims at clarifying the broad-spectrum antibacterial effect of endophytic Bacillus amyloliquefaciens strain P-r21, and determining its control effect on tomato gray mold. In this study, the fermentation conditions of strain P-r21 were optimized. The antibacterial activity of strain P-r21 against six pathogens and its inhibition on spore germination of Botrytis cinerea were determined by plate confrontation method, and its control effect on tomato gray mold was studied by in vitro inoculation test. The results showed that: the optimum fermentation media was PYJ, and the optimum condition was initial pH 6.0 and fermentation time of 12 h. Strain P-r21 exhibited antagonistic ability to six plant pathogens (Botrytis cinerea, Fusarium proliferatum, Rhizoctonia cerealis, Gaeumannomyces graminis, Fusarium graminearum, and Colletotrichum karstii). The inhibition effects of the strain on the growth of C. karstii and B. cinerea were the strongest, and the inhibition rates were 88.0% and 84.5%, respectively. The inhibition rate of B. cinerea spore germination treated with fermentation filtrate was 80.6%. The control effects on tomato gray mold disease of leaves and fruits treated with fermentation filtrate were 100% and 80.0%, respectively. The control effect of fermentation filtrate diluted 10 times could reach 67.1% and 60.7%, respectively. This study clarifies that strain P-r21 has broad-spectrum antibacterial effect and can be used for the control of tomato gray mold. The study lays a foundation for the application of this strain in the biological control of plant diseases.

Key words: Bacillus amyloliquefaciens, Botrytis cinerea, biological control, optimization of fermentation conditions, broad-spectrum antibacterial effect